Technical note: Bremsstrahlung dose in the electron beam at extended distances in total skin electron therapy

Ding, G; Dogan, Serpil K; Das, Indra J.

doi:10.1002/mp.15433

Cited by 2 publications

(4 citation statements)

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“…However, a recent study by Ding et al 22 showed that bremsstrahlung dose was < 1% even at SSD = 500 cm and that the common belief of up to 5% bremsstrahlung dose at large extended distances is incorrect. 22 Previously reported high bremsstrahlung doses 21 might be due to poor signal-to-noise ratio for measuring very low dose.…”

Section: Discussionmentioning

confidence: 99%

“…showed that bremsstrahlung dose was < 1% even at SSD = 500 cm and that the common belief of up to 5% bremsstrahlung dose at large extended distances is incorrect 22 . Previously reported high bremsstrahlung doses 21 might be due to poor signal‐to‐noise ratio for measuring very low dose 22 . Therefore, the x‐ray contamination to patient is no longer a limiting factor for TSET at large extended distances.…”

Section: Discussionmentioning

confidence: 99%

“…22 Previously reported high bremsstrahlung doses 21 might be due to poor signal-to-noise ratio for measuring very low dose. 22 Therefore, the x-ray contamination to patient is no longer a limiting factor for TSET at large extended distances. This study also confirms that bremsstrahlung dose contributing to the deeper tissues was < 1% of skin dose in both beam delivery techniques as shown in the dose profiles of Figure 2d.…”

Section: Discussionmentioning

confidence: 99%

“…Since Das et al 21 reported a 5% bremsstrahlung dose for a 6 MeV electron beam at extended distance of 500 cm it has been accepted as common knowledge. However, a recent study by Ding et al 22 . showed that bremsstrahlung dose was < 1% even at SSD = 500 cm and that the common belief of up to 5% bremsstrahlung dose at large extended distances is incorrect 22 .…”

Section: Discussionmentioning

confidence: 99%

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Skin dose distributions between Stanford and rotational techniques in total skin electron therapy (TSET)

et al. 2022

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Total skin electron therapy (TSET) has proven to be one of the most effective treatments for advanced-stage cutaneous T-cell lymphoma. Two most used techniques are the Stanford six-field and rotational techniques. This study compares patient skin dose distributions as a function of depth between these two techniques. Methods: The EGSnrc system was used to simulate electron beams and calculate patient dose distributions. The calculations assumed the same patient standing on a platform, and the patient's different postures were ignored for the Stanford technique in the comparison of dose distributions. The skin doses were analyzed as a function of skin depth-dose coverage and evaluated using dosevolume-histograms (DVH). The comparisons were performed in three realistic clinical settings in which dual-field were used for patients treated at extended distances of 316 and 500 cm, and a single field was used at 700 cm. In all cases the realistic patient treatment beam delivery geometry was simulated. Results: Although small dose differences were observed in some local areas, no clinically significant differences were found in the patient 3D dose distributions between the Stanford and rotational techniques. Virtually the same DVH curves between two the techniques were observed for mean dose to skin depth of 0-5, 5-10, and 10-15 mm from the skin surface, respectively. It is found that the skin depth dose coverage is 2 mm shallower for patient treatment at 500 cm compared to at 316 cm due to the additional air attenuation. However, very similar dose coverage and uniformity can be achieved at these two different extended treatment distances by adjusting the thickness of acrylic scatter plate. Adequate thickness of a scattering plate improves the skin dose uniformity. Conclusion: Both the Stanford and rotational techniques deliver very similar skin dose coverage in DVH plots, and only small differences are seen in local areas. It is worth to emphasize that the DVH is a graphical representation of the distribution of dose within a structure, and it does not contain spatial information. Therefore, comparison of entire skin dose using DVH may mask some variations at different locations of the surface area. In addition, the comparison did not consider different patient postures of the Stanford technique. Including the different patient postures in the calculation may affect the result of doses to the limbs. K E Y W O R D S Monte Carlo, patient skin dose distributions, rotational technique, stanford technique, total skin electron therapy 6646

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Skin dose distributions between Stanford and rotational techniques in total skin electron therapy (TSET)

et al. 2022

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A scattering‐foil free electron beam to increase dose rate for total skin electron therapy (TSET)

Ding,

Chen,

Homann

2024

Medical Physics

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BackgroundElectron beams are used at extended distances ranging between 300 to 700 cm to uniformly cover the entirety of the patient's skin for total skin electron therapy (TSET). Even with electron beams utilizing the high dose rate total skin electron (HDTSe) mode from the Varian 23iX or TrueBeam accelerators, the dose rate is only 2500 cGy/min at source‐to‐surface distance (SSD) = 100 cm. At extended distances, the decrease in dose rate leads to long beam delivery times that can limit or even prevent the use of the treatment for patients who, in their weakened condition, may be unable to stand on their own for extended periods of time. Previously, to increase dose rate, a customized 6 MeV electron beam was created by removing the x‐ray target, flattening filter, beam monitor chamber, and so forth. from the beam path (Chen, et at IJROBP 59, 2004) for TSET. Using this scattering‐foil free (SFF) electron beam requires the treatment distance be extended to 700 cm to achieve dose uniformity from the single beam. This room size requirement has limited the widespread use of the 6 MeV‐SFF beam.PurposeThis study explores an application of a dual‐field technique with a 6 MeV‐SFF beam to provide broad and uniform electron fields to reduce the treatment distances in order to overcome treatment room size limitations.MethodsThe EGSnrc system was used to generate incident beams. Gantry angles between 6 MeV‐SFF dual‐fields were optimized to achieve the similar patient skin dose distribution resulting from a standard 6 MeV‐HDTSe dual‐field configuration. The patient skin dose comparisons were performed based on the patient treatment setup geometries using dose‐volume‐histograms.ResultsSimilar dose coverage can be achieved between 6 MeV‐SFF and 6 MeV‐HDTSe beams by reducing gantry angles between dual‐field geometries by 8° and 7° at treatment distances of 400 and 500 cm, respectively. To achieve 95% mean dose to the first 5 mm of skin depth in the torso area, the mean dose to depths of 5–10 mm and 10–15 mm below the skin surface was 74% (74%) and 49% (50%) of the prescribed dose when using 6 MeV‐SFF (6 MeV‐HDTSe) beam, respectively.ConclusionsThe 6 MeV‐SFF electron beam is feasible to provide similar TSET skin dose coverage at SSD ≥ 400 cm using a dual‐field technique. The dose rate of the 6 MeV‐SFF beam is about 4 times that of current available 6 MeV‐HDTSe beams at treatment distances of 400–500 cm, which significantly shortens the treatment beam‐on time and makes TSET available to patients in weakened conditions.

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Technical note: Bremsstrahlung dose in the electron beam at extended distances in total skin electron therapy

Cited by 2 publications

References 37 publications

Skin dose distributions between Stanford and rotational techniques in total skin electron therapy (TSET)

Skin dose distributions between Stanford and rotational techniques in total skin electron therapy (TSET)

A scattering‐foil free electron beam to increase dose rate for total skin electron therapy (TSET)

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